1. Field of the Invention
This invention relates to a method for sweetening chewing gum with an L-aspartic acid sweetening derivative and to products obtained thereby.
2. Description of the Prior Art
Aspartame, L-aspartyl-L-phenylalanine methyl ester, a derivative of L-aspartic acid, has recently been approved by the Food and Drug Administration as a natural sweetener for use in food. It ordinarily is unstable when incorporated in chewing gum. Aspartame decomposes in the presence of moisture and reacts with aldehyde-containing flavorings, such as cinnamon, over extended periods of time. Thus, chewing gum compositions obtained by admixing the aspartame with gum base and other chewing gum ingredients prior to the conventional rolling and extrusion steps exhibit substantial loss of sweetening. To obtain acceptable sweetening levels over extended periods, an inordinate amount of aspartame must be used to compensate for subsequent losses.
Attempts have been made to protect aspartame from mositure and gum components by encapsulating a solid aspartame with coating materials such as cellulose ethers, cellulose esters, edible vinyl polymers, gelatin, and the like, as disclosed in U.S. Pat. No. 4,384,004, U.S. Pat. No. 4,122,195 and U.S. Pat. No. 4,139,639. The encapsulated aspartame is incorporated in the chewing gum. However, even when encapsulated aspartame is incorporated into the gum, substantial decomposition of the aspartame results. It is believed that the integrity of the encapsulation is: (1) physically destroyed during mixing, and (2) destroyed by dissolution into gum ingredients such as plasticizers. Decomposition of the aspartame over time could also result from migration of gum components through the encapsulant.
In U.S. Pat. No. 4,374,858 the sweetness stability of aspartame in chewing gum is improved by applying onto the surface of the chewing gum piece a dusting of a material comprising aspartame. The aspartame is applied in pure powdered form, in encapsulated form or combinations thereof. The dusting can be by means of gravity flow induced by a helical auger, or by rollers. However, drawbacks in coating the aspartame onto the chewing gum surface in dry form in the manner taught by U.S. Pat. No. 4,374,858 are: (1) physical loss of the aspartame from the surface during subsequent material handling steps such as transport of the coated gum to wrapping equipment and the wrapping operation, (2) inconsistent control of the amount of aspartame applied to the gum surface and (3) an undesirably strong initial sweetness impact.
The present invention provides an economical process for sweetening chewing gum with an L-aspartic acid sweetening derivative, such as L-aspartyl-L-phenylalanine methyl ester (aspartame) which achieves accurate and consistent control over the amount of the sweetener applied to the chewing gum, minimizes physical loss of the sweetener during subsequent material handling steps, and minimizes decomposition of the sweetener during both chewing gum manufacture and storage of the finished product.
The aspartame sweetened gum of the present invention does not contain "hot spots" due to high concentrations of the sweetener in or on the chewing gum. An acceptable level of sweetness is exhibited by the products during their shelf lives of at least about six months.